Workshop Invariants

Placeholders: {INVENTORY} = the skill’s frozen discovery artifact (heroku-resource-inventory.json / gcp-resource-inventory.json); {SKILL_LABEL} = “Heroku” / “GCP”.

1. Discovery is frozen

• The workshop NEVER writes {INVENTORY}, capture directories, or any discovery-derived analysis artifact (coupling, preflight, clusters).
• scenarios/index.json.inventory_fingerprint = SHA-256 hex of the raw {INVENTORY} bytes (no JSON re-serialization), recorded at baseline capture.
• Every Apply & reprice MUST recompute the fingerprint first and ABORT with “Inventory changed since baseline. Re-run Discover before workshop reprice.” on any difference.

2. Sidebar state semantics

• The workshop is a sidebar: it NEVER becomes current_phase. Entry sets phases.workshop: "in_progress"; current_phase stays at "estimate" until exit/decline.
• Exit (assembler): phases.workshop: "completed". Skills WITHOUT a post-Estimate decision gate advance current_phase to "generate". Skills that DEFINE a decision gate re-present that gate — never auto-advance to Generate (the gate sets the next state from the user’s choice). Decline at the offer: same, without requiring scenarios/.
• Warm-start rule: current_phase == "estimate" AND phases.estimate == "completed" AND phases.workshop == "pending" → present the workshop offer; NEVER recompute Estimate.
• The hold-Generate rule above is DECLARED, not just prose: the workshop phase’s frontmatter carries _gates: generate (INTERPRETER.md § _gates), so Generate must not start while phases.workshop is unresolved. Declining resolves the sidebar ("completed") and lifts the gate.
• If Generate (or later) is already completed, apply the Estimate re-entry guard (confirm → reset downstream to pending) before any refresh.

3. Inner runs are artifact-only

When the refresh re-runs a backbone phase (Design/Recommend/Estimate) to reprice:

4. Scenario store

• Max 5 scenarios. Before evicting, WARN and NAME the victim (id + label); never delete baseline_scenario_id unless the user explicitly resets.
• Working tree == active scenario: the skill’s preference/design/estimate artifacts always match index.active_scenario_id.
• Each manifest’s estimation_summary carries at minimum: aws_monthly_premium / _balanced / _optimized, complexity_tier, pricing_source, region_note (nullable), calculator_url (nullable). Optional: recommendation_outcome (nullable — copy of recommendation.outcome when the inner estimate wrote v2 decision fields; compare views may render an Outcome column and flag flips vs baseline).
• preferences_subset records ONLY the knob paths that differ from baseline.

5. Region honesty

The sheet always shows: numbers stay on the us-east-1 cache basis and every affected estimate carries a region_note. Regional dollar deltas are not available (no live pricing access). Never present cache-based numbers as regional.

6. Shareable calculator link

No shareable AWS Pricing Calculator link is produced. calculator_url is always null. No calculator MCP is configured.

Compare tables and stakeholder reports omit the calculator link line (all calculator_url values are null).